When the Beatles released "Yesterday and Today" in 1966, with its cover of the boys holding mutilated baby dolls, San Francisco teenager Eric Christensen grabbed a poster of it before the album art could be pulled from the shelves.

Forty-five years later, Christensen was a documentary filmmaker in need of a project. So he went downstairs to the vinyl room of his Mill Valley home and looked at that famous "butcher" poster, framed in the center of the wall. Then he looked at the rows and rows of records on either side of it - 10,000 of them, alphabetized by artist. Then his next project was obvious: "The Cover Story: Album Art," which receives its world premiere Saturday.

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It was all on the wall in front of him so he started at letter A, and didn't need to go past B before he found the dramatic device that would carry the picture. Just past the Beatles he saw another scandalous cover, the topless preteen holding a model airplane on the cover of the original Blind Faith record, released in 1969.

"Who is this girl?" says Christensen, who is 64 but still boyish when it comes to his records. "I knew if I could find her and get her to talk about posing for the cover, I would have a centerpiece for a documentary about album cover art."

The spoiler alert is that Christensen, without even a name to go on, sleuthed out the girl and a tale of intrigue that involves a wrecked Rolls-Royce, a horse, the London subway and an international reunion of sisters at a Big Sur retreat. That episode is worthy of its own short film, but instead it gives the mystery to a long one.

"The Cover Story" debuts at Sweetwater Music Hall, which is the right place to give the film a push. Opened a year ago by Bob Weir and friends, the made-over Masonic Hall, off the Mill Valley town square, is a safe place for hippies. Hang around the bar, and you will find people still listening to LPs and studying the art in the gatefold, probably for several hours that same day.

Access to musicians

There are Sweetwater regulars in front of the camera and behind it. These include Christensen, who has been in the scene since he was at Lowell High School, with an after-school job mailing out records for "Big Daddy" Tom Donahue, the godfather of FM underground. Now a retired KGO TV producer who also made films for Bill Graham, Christensen had no trouble getting access to performers.

"A lot of musicians are tired of getting the same old rock 'n' roll questions," he says, "but very seldom are they asked about their album covers."

Joni Mitchell turned him down, but Yoko Ono did not. To hear her describe what compelled Ono and John Lennon to pose naked, front and back, for the cover of "Two Virgins," he was willing to fly to New York, even after he'd had to eat the ticket when she canceled their first meeting.

Ono made up for it by volunteering to discuss her album cover for "Season of Glass," which displayed the bloody lenses removed from Lennon's face the night he was shot to death.

"She was the most expensive part of the film," Christensen says, "but that story made the hairs stand up on the back of my neck."

He had to book a studio for that interview, but other great visual artists were at Christensen's disposal. They all have time.

Doors, Nirvana covers

In the film, photographer Henry Diltz describes how the Doors couldn't get in the door of the Morrison Hotel, on Los Angeles' Skid Row. So they waited outside in the smog until the desk clerk, who had refused them, went up in the elevator. They had the cover shot and were gone before the elevator came back down. In celebration, they hit the first bar they saw, which happened be called the Hard Rock Cafe. On impulse, Diltz shot the name painted on glass for the back cover.

Spencer Elden, who was the naked baby reaching for the dollar bill in the swimming pool, on the cover of the Nirvana album "Nevermind," has talked before. Now 22, Elden wants to be paid for it, but Christensen got around that by agreeing to buy some of his paintings.

To finance that purchase and the film in general, Christensen had to sell some of his vintage posters from the Fillmore and Avalon era. That diminished his poster supply to just under 1,000. He's been around since before the Summer of Love, picking up home movies and concert footage, which he stores in his basement, near the posters. Some of his tape made it into his previous documentary, "The Trips Festival Movie," which came out five years ago.

"I call myself an accumulator rather than a collector," he says. "I just get things that come my way."

He has sealed copies of records he's bought for the cover and never played. One is "He's Able" by the People's Temple Choir, photographed at Portals of the Past in Golden Gate Park. "Our inspiration," reads the back cover, "is a lifestyle demonstrated by our pastor James W. Jones."

Reduction of artwork

You won't find that on CD, a format that the illustrators who appear in the film - Stanley Mouse, Victor Moscoso, R. Crumb - wish had never been invented.

"Calling it a jewel box is rubbish," says Roger Dean, who designed the otherworldly covers for Yes. "It's a tack(y) box."

Victor Kahn, who designed covers for the Rolling Stones and Jimi Hendrix, has to stop and compose himself before he will even address the concept. "Oh, my God. Excuse me. I hate CDs," he says. The illustrators can't find words to describe the further reduction of their artwork onto a tablet or a phone. So Huey Lewis does it for them.

"All of this is precluded by iTunes," he says. "Forget the album art. They don't even listen to the album."

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